Hyporeninemia, aldosteronism and hypertension, the characteristic features of primary aldosteronism, also characterize the rare disorder, dexamethasone-suppressible aldosteronism. This disorder is familial with an autosomal dominant mode of inheritance which is not HLA linked. As treatment with dexamethasone corrects the aldosteronism and hypertension and restores the responsiveness of the renin-angiotensin system, and as treatment with adrenocorticotrophin (ACTH) produces a sustained increase in aldosterone production and blood pressure, this suggests that the aldosteronism and hypertension are ACTH-dependent. The cause of the ACTH dependence of alodsterone production is unknown but may represent stimulation rather than the usual inhibition by ACTH of 11-hydroxylation and 18-hydroxylation in zona glomerulosa cells. As aminoglutethimide, which blocks selectively steroidogenesis by the zona glomerulosa, pregnancy, which results in an increased production of an aldosterone antagonist, progesterone, and spironolactone, an aldosterone antagonist, correct the hypertension, this suggests that aldosterone alone or in combination with related steroids from the zona glomerulosa mediate the hypertension.